The present invention relates to an apparatus and a method for controlling an intake system in an engine.
In an earlier V-type engine disclosed in a Japanese Examined Utility Publication No. 4-8304, a control valve is disposed in a partition wall that partitions connection between intake collectors on the banks of the engine wherein the control valve is opened when an engine rotation speed is more than a predetermined value, thereby enlarging a collector capacity per a single cylinder and improving an engine output at a fully opened position of a throttle valve during an intermediate- and high-rotation speed range of the engine.
An intake collector apparatus shown in a Japanese Unpublished Patent Application No. 2001-307122, in order to improve an engine output at a fully opening position of a throttle valve, has a main collector and a sub collector that is connected thereto through a control valve for collector capacity wherein the collector capacity varies by opening and closing the control valve corresponding to an engine rotation speed and as a result, both a torque response in a low-engine rotation speed range and an engine output at a fully opened position of a throttle valve in a high-engine rotation speed range are expected to improve.
However, in the above intake collector apparatus a pressure of the sub collector becomes lower than a pressure of the main collector depending upon an engine operation condition so that air introduced into the main collector through the throttle valve pulls in the sub collector, bringing in a large torque reduction and deterioration of an engine performance due thereto.
Namely, at a fully opened position of the throttle valve where the collector capacity is maximized by opening the control valve for the collector capacity, the throttle valve is controlled to become fully closed to suddenly stop a vehicle, and then, a little while later the control valve closes. At this moment the pressure of the main collector and the pressure of the sub collector are both negative. Afterwards, when the throttle valve opens for re-acceleration the pressure of the main collector increases and a little bit thereafter, the control valve opens. However, the negative pressure of the sub collector still remains larger compared with the pressure of the main collector and therefore, the air introduced into the main collector through the throttle valve pulls in the sub collector.
The present invention provides an apparatus and a method for controlling an intake system in an engine in order to solve the foregoing problems.
As one aspect of the present invention, a difference in pressure between a main collector and a sub collector is reduced when a condition that pressure in the sub collector relative to pressure in the main collector is lower than a predetermined value occurs.
The other aspects and features of this invention will become understood from the following description with accompanying drawings.